In order to burn fuel in an internal combustion engine, a gas, for example, (compressed) air, and optionally also exhaust gas, is fed to a combustion chamber (e.g. to one or more cylinders) of the internal combustion engine. The gas that is fed to the internal combustion engine for purposes of burning the fuel will also be referred to below as charge gas, and it can contain air, especially compressed air, as well as exhaust gas. In order to achieve a high degree of combustion, it can be advantageous to keep the temperature of the charge gas below a certain level so as to achieve a certain threshold density of the charge gas. Due to the environmental influences and/or due to the exhaust gas that has been admixed to the charge gas, the temperature of the charge gas can vary markedly, rapidly fluctuating, for instance, within a range from 50 milliseconds to 0.5 seconds by a factor of between 2 and 10, particularly depending on the required driving torque and/or on the driving output.
In order to suitably cool the charge gas before it is fed into the combustion chamber of the internal combustion engine, the state of the art makes use of a charge gas cooling system. In this context, a coolant that is conveyed by a pump flows through a heat exchanger around which the charge gas flows, and the coolant then flows through a vehicle cooler, especially a low-temperature cooler, for purposes of cooling the coolant.
It has been noted that, in conventional charge air cooling systems, the gas that flows out after the heat exchange with the heat exchanger can reach relatively high temperatures, particularly in the case of highly fluctuating demands in terms of the driving output. In this process, the coolant might even come to a boil at the outlet of the charge air cooler.
In order to alleviate this problem, the state of the art makes use of a model-based feedforward control, including a PID (proportional-integral-derivative) controller.
The conventionally executed methods, however, typically only attain a slow and late correction of the cooling, which can cause the coolant to come to a boil or boil dry, especially in dynamic load ranges, that is to say, rapid and highly fluctuating demands in terms of the driving output. In some cases, the state of the art dispenses with monitoring the intake pipe temperature and/or with regulating the intake pipe temperature.
Due to the excessively high temperature of the charge air, the combustion inside the combustion chambers of the internal combustion engine cannot be optimally carried out and/or controlled under all conditions. In EGR (exhaust gas recirculation) concepts, if the charge air temperature is too low, the temperature can fall below the dew point, causing sooting of the charge gas cooler. For this reason, the coolant pump is used to regulate the value to empirically ascertained target temperatures for the charge gas.